Vehicle transmission having manually shifted lower gears and automatically shifted higher gears

ABSTRACT

A transmission includes a plurality of shift rails, each of which is axially movable forwardly and rearwardly from a center neutral position to respective gear engaging positions. The lower shift rails are provided for manual shifting among the lower gear ratios of the transmission. The highest shift rail is provided for selective manual or automatic shifting among the highest two gear ratios of the transmission. An idler rail is disposed adjacent to the highest shift rail. For manual shifting, the idler rail is connected to the highest shift rail, and a manually operable shift lever is used to move both the idler rail and the highest shift rail. For automatic shifting, the idler rail is disconnected from the highest shift rail, and an automatic shift member is moved into cooperation with the highest shift rail. Rotation of the automatic shift shaft causes corresponding movement of the automatic shift member. An electronic controller is provided for controlling the automatic shifting of the transmission in response to sensed operating conditions of the vehicle. A circuit is provided for sensing the rotational position of the automatic shift shaft and for generating an electrical signal which is representative of the actual position thereof, which is also representative of the actual position of the highest shift rail, to the electronic controller.

This is a divisional of copending application Ser. No. 08/147,283 filedon Nov. 3, 1993.

BACKGROUND OF THE INVENTION

This invention relates in general to vehicle transmissions and inparticular to an improved transmission structure wherein the lower gearratios are shifted manually and wherein the higher gear ratios can beshifted either manually or automatically as desired.

In most vehicles, a transmission is provided in the drive train betweenthe engine and the driven wheels. As is well known, the transmissionincludes a case containing an input shaft, an output shaft, and aplurality of meshing gears. Means are provided for connecting selectedones of the meshing gears between the input shaft and the output shaftto provide a desired speed reduction gear ratio therebetween. Themeshing gears contained within the transmission case are of varying sizeso as to provide a plurality of such gear ratios. By appropriateselection of these gear ratios, acceleration and deceleration of thevehicle can be accomplished in a smooth and efficient manner.

Many transmission structures are known in the art for performing thisgear ratio selection manually, i.e., in response to some physicalexertion by the vehicle driver. In a conventional manual transmission,the driver grasps and moves an upper portion of a pivotable shift lever.In response thereto, a lower portion of the shift lever is moved intoselective engagement with one of a plurality of shift rails providedwithin the transmission. Thus, movement of the shift lever causesmovement of the selected one of the shift rails. Movement of theselected shift rail causes certain ones of the meshing gears to beconnected between the input shaft and the output shaft so as to providethe desired gear ratio therebetween.

Many transmission structures are also known in the art for performingthis gear ratio selection automatically, i.e., without any physicalexertion by the vehicle driver. In a conventional automatictransmission, the shift rails are typically replaced by a plurality ofhydraulically or pneumatically actuated structures. In response topredetermined operating conditions, these structures cause certain onesof the meshing gears to be connected between the input shaft and theoutput shaft so as to provide the desired gear ratio therebetween.Although automatic transmissions offer the advantages of increasedconvenience of use and reduced fatigue for the driver, manualtransmissions provide the advantages of decreased cost, increased torquecapacity, and better fuel economy. Because of this, the majority ofmedium and heavy duty truck transmissions in common use today are manualtransmissions.

In order to improve the convenience of use of manual transmissions,various structures have been proposed for fully or partially automatingthe shifting of an otherwise conventional manual transmission. In afully automated manual transmission, the conventional driver operatedshift lever is usually replaced by one or more hydraulically orpneumatically controlled automatic shifting mechanisms. The componentsof the fully automatic transmission function to shift all of the shiftrails within the transmission throughout all of the gear ratios. In apartially automated manual transmission, the conventional driveroperated shift lever is usually supplemented with one or morehydraulically or pneumatically controlled automatic shifting mechanisms.The components of the partially automated transmission function to shiftonly a selected few of the shift rails within the transmissionthroughout the selected few of the gear ratios which are available fromsuch shift rails. Typically, the lower gear ratios are manually selectedby the vehicle driver, while the higher gear ratios are automaticallyselected. Such an approach is advantageous because the partiallyautomated transmission is lower in cost than a comparable fullyautomated manual transmission, yet offers automatic shifting in thehigher gear ratios where the majority of shifting between gears normallyoccurs.

As mentioned above, various structures have been proposed for fully orpartially automating the shifting of an otherwise conventional manualtransmission. However, such known structures have been found to beunduly complicated and expensive. Thus, it would be desirable to providean improved partially automated transmission which is simpler and lessexpensive than known structures.

SUMMARY OF THE INVENTION

This invention relates to an improved transmission structure wherein thelower gear ratios are shifted manually and wherein the higher gearratios can be shifted either manually or automatically as desired. Thetransmission includes a plurality of shift rails, each of which isaxially movable forwardly and rearwardly from a center neutral positionto respective gear engaging positions. The lower shift rails areprovided for manual shifting among the lower gear ratios of thetransmission. The highest shift rail is provided for selective manual orautomatic shifting among the highest two gear ratios of thetransmission. To accomplish this, an idler rail is disposed adjacent tothe highest shift rail. Means are provided for selectively connectingthe idler rail to the highest shift rail for axial movement therewith.For manual shifting, the idler rail is initially connected to thehighest shift rail for axial movement therewith. Then, a manuallyoperable shift lever is used to move the idler rail, as well as thehighest shift rail connected thereto, among the highest two gear ratiosof the transmission. For automatic shifting, the idler rail is initiallydisconnected from the highest shift rail. At the same time, an automaticshift member mounted on a rotatable automatic shift shaft is moved intocooperation with the highest shift rail. Rotation of the automatic shiftshaft causes corresponding movement of the automatic shift member. As aresult, the highest shift rail is moved among the highest two gearratios of the transmission. An electronic controller is provided forcontrolling the automatic shifting of the transmission in response tosensed operating conditions of the vehicle. Means are provided forsensing the rotational position of the automatic shift shaft and forgenerating an electrical signal which is representative of the actualposition thereof, which is also representative of the actual position ofthe highest shift rail, to the electronic controller.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary side elevational view, partially in crosssection, of the top portion of a vehicle transmission in accordance withthis invention.

FIG. 2 is a rear end sectional view taken along line 2--2 of FIG. 1showing the components of a manual/automatic selector assembly in afirst position for operation in a manual shifting mode, and furthershowing a simplified schematic diagram of a fluid actuated controlcircuit in a first operating condition.

FIG. 3 is a rear end sectional view similar to FIG. 2 showing thecomponents of the manual/automatic selector assembly in a secondposition for operation in an automatic shifting mode, and furthershowing the associated simplified schematic diagram of the fluidactuated control circuit in a second operating condition.

FIG. 4 is a top sectional view taken along line 4--4 of FIG. 3 of themanual/automatic selector assembly and an automatic shifting assembly.

FIG. 5 is a rear sectional view taken along line 5--5 of FIG. 4 showingthe components of the automatic shifting assembly in a neutral position.

FIG. 6 is a rear sectional view similar to FIG. 5 showing the componentsof the automatic shifting assembly in a gear engaging position.

FIG. 7 is a top plan view of the automatic shift member illustrated inFIGS. 1 through 4.

FIG. 8 is a side elevational view of the automatic shift meterillustrated in FIG. 7.

FIG. 9 is a top plan view of the manual shift member illustrated inFIGS. 1 through 4.

FIG. 10 is a side elevational view of the manual shift memberillustrated in FIG. 9.

FIG. 11 is an enlarged side sectional view of the automatic shiftposition sensor illustrated in FIG. 2, wherein the manual shift fingeris shown in a neutral position.

FIG. 12 is an enlarged side sectional view of the automatic shiftposition sensor illustrated in FIG. 11, wherein the manual shift fingeris shown in a gear engaging position, and wherein the combined assemblyof the automatic shift member and the manual shift member are located inthe first position illustrated in FIG. 2 for manual operation.

FIG. 13 is an enlarged side sectional view of the automatic shiftposition sensor illustrated in FIG. 11, wherein the manual shift fingeris shown in a gear engaging position, and wherein the combined assemblyof the automatic shift member and the manual shift member are located inthe second position illustrated in FIG. 3 for automatic operation.

FIG. 14 is a simplified schematic diagram of a fluid control system foruse with the compound transmission embodiment of this invention.

FIG. 15 is a top plan view of the shift lever restraining plate andinterlock bracket illustrated in FIG. 1.

FIG. 16 is a sectional elevational view taken along line 16--16 of FIG.15 showing the shift lever restraining plate and interlock bracket,together with a portion of the shift lever in engagement with the idlerrail.

FIG. 17 is a sectional elevational view similar to FIG. 16 showing theshift lever restraining plate and interlock bracket, together with aportion of the shift lever in engagement with the second shift rail.

FIG. 18 is a fragmentary side sectional view taken along line 18--18 ofFIG. 2 showing the means for sensing the rotational position of theautomatic shift shaft.

FIG. 19 is a simplified schematic diagram of an electronic controlcircuit for use with the transmission of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

1. Basic Transmission Structure

Referring now to the drawings, FIGS. 1 through 4 illustrate the basicstructure of an upper portion of a vehicle transmission, indicatedgenerally at 10, in accordance with this invention. The non-illustratedlower portion of the transmission 10, which includes a plurality ofmeshing gears mounted on main and counter shafts, is conventional in theart and is so well known that a discussion thereof is not necessary fora full and complete understanding of this invention. The transmission 10includes a case 11 having an opening 11a formed through the upperportion thereof. A shift housing 12 is secured to the upper portion ofthe case 11 about the opening 11a by any conventional means. The uppersurface of the shift housing 12 has a mounting surface 13 definedthereon, to which a conventional shift tower assembly (not shown) can besecured by any conventional means.

As is well known, a manually operable shift lever (a lower end of whichis illustrated at 14 in FIG. 1) is mounted on the shift tower assemblyfor pivoting movement relative thereto. The upper end of the shift lever14 extends upwardly into a vehicle cab (not shown) where it can beeasily grasped and moved by a driver. The lower end of the shift lever14 extends downwardly through the shift housing 12 and the opening 11aformed through the case 11 into the transmission 10. Alternatively, themanually operable shift lever 14 may be replaced by a conventionalremote actuator (not shown) having a lower end which also extendsdownwardly through the shift housing 12 and the opening 11a into thetransmission 10.

As best shown in FIGS. 2, 3, and 4, a plurality of shift rails 20, 21,and 22 are provided within the transmission 10. The ends of the shiftrails 20, 21, and 22 are respectively supported for axial movement byfront and rear rail support members 23 and 24 (see FIG. 1). The frontand rear rail support members 23 and 24 are secured to the transmissioncase 11 and have respective openings formed therethrough for slidablyreceiving the ends of the shift rails 20, 21, and 22 therein. Each ofthe shift rails 20, 21, and 22 is axially movable from a central neutralposition to either a forward position (to the left when viewing FIG. 1)to engage a first gear ratio or to a rearward position (toward the rightwhen viewing FIG. 1) to engage a second gear ratio.

A forward notch 20a is formed in the upper surface of the first shiftrail 20. Similarly, forward notches 21a and 22a are formed in the uppersurfaces of the second and third shift rails 21 and 22, respectively. Asbest shown in FIG. 1, the forward notches 20a, 21a, and 22a are alignedwith one another in a direction which is transverse to the longitudinalaxes of the shift rails 20, 21, and 22 when such shift rails 20, 21, and22 are all in their neutral positions. Similarly, rearward notches 20b,21b, and 22b are respectively formed in the upper surfaces of the shiftrails 20, 21, and 22. The rearward notches 20b, 21b, and 22b are alsoaligned with one another in a direction which is transverse to thelongitudinal axes of the shift rails 20, 21, and 22 when such shiftrails 20, 21, and 22 are all in their neutral positions. The purposes ofthe forward notches 20a, 21a, and 22a and the rearward notches 20b, 21b,22b will explained below.

A first shift fork 25 is connected to the first shift rail 20 by rivetsor other conventional means for movement therewith. Similarly, a secondshift fork 26 is connected to the second shift rail 21, and a thirdshift fork 27 is connected to the third shift rail 22. The shift forks25, 26, and 27 extend downwardly from their associated shift rails 20,21, and 22 into engagement with respective gear engaging mechanisms (notshown) provided in the lower portion of the transmission 10. The shiftforks 25, 26, and 27 and the gear engaging mechanisms are conventionalin the art.

The components of the transmission 10 thus far described constitute thebasic structure of the main section of the transmission 10, whichprovides a predetermined number of speed reduction gear ratios betweenthe input and output shafts thereof (not shown). In the illustratedembodiment, the first shift rail 20 is provided for shifting betweenreverse and first gear ratios, the second shift rail 21 is provided forshifting between second and third gear ratios, and the third shift rail22 is provided for shifting between fourth and fifth gear ratios. Thus,the illustrated main section of the transmission 10 is a five-speedtransmission.

The transmission 10 may, if desired, further include an auxiliarysection (not shown) located rearwardly (toward the right when viewingFIG. 1) of the main section. The auxiliary section is conventional inthe art and, similar to the main section, provides a predeterminednumber of gear ratios in a known manner. The output shaft of the mainsection constitutes the input shaft to the auxiliary section. Thus, asis well known, the total number of gear ratios available from thetransmission 10 as a whole is equal to the product of the number of gearratios available from the main section and the number of gear ratiosavailable from the auxiliary section.

For example, if the auxiliary section of the transmission 10 describedabove is a conventional two-speed range section, then a total of tenforward gear ratios is available from the transmission 10 as a whole.When the range section of the transmission 10 is shifted to a low gearrange, movement of the shift rails 20, 21, and 22 provides the fivelower gear ratios as described above. When the range section of thetransmission 10 is shifted to a high gear range, movement of the shiftrails 20, 21, and 22 provides five additional higher gear ratios. In thehigh range, the first shift rail 20 is provided for shifting to thesixth gear ratio, the second shift rail 21 is provided for shiftingbetween seventh and eighth gear ratios, and the third shift rail 22 isprovided for shifting between ninth and tenth gear ratios. Although thisinvention will be described and illustrated in the context of theillustrated ten speed transmission 10 wherein shifting between the toptwo (ninth and tenth) gear ratios is selectively automated, it will beappreciated that this invention may be used in conjunction with anyother conventional transmission structure, both single stage andcompound.

2. Basic Transmission Operation

As discussed above, the shift tower assembly of the transmission 10supports the shift lever 14 for pivoting movement therein. The upper endof the shift lever 14 extends upwardly into a vehicle cab where it canbe easily grasped and moved by a driver. The lower end of the shiftlever 14 extends downwardly through the shift housing 12 and the opening11a into the transmission 10. In a conventional manual transmission, thelower end of the shift lever 14 would selectively cooperate with theforward notches 20a, 21a, and 22a respectively formed in the uppersurfaces of the shift rails 20, 21, and 22. To operate such aconventional manual transmission, the driver would initially select oneof the three shift rails 20, 21, and 22 for movement. This would beaccomplished by initially pivoting the lower end of the shift lever 14in a direction which is transverse to the longitudinal axes of the shiftrails 20, 21, and 22. By appropriate pivoting movement in this selectingdirection, the lower end of the shift lever 14 would be positioned in asingle one of the notches 20a, 21a, and 22a of the shift rails 20, 21,and 22, respectively.

Following this initial selection movement, the driver would then shiftthe selected shift rail 20, 21, and 22 by pivoting the lower end of theshift lever 14 in a direction which is parallel to the longitudinal axesthereof. By appropriate pivoting movement in this shifting direction,the selected one of the shift rails 20, 21, and 22 would be movedaxially forwardly or rearwardly from the central neutral position. As aresult, one or the other of the gear ratios available from the selectedshift rail 20, 21, and 22 would be engaged, as described above.

This invention, however, relates to a mechanism for permitting thisselecting and shifting movement to occur not only manually, but alsoautomatically so as to not require any manual effort on the part of thedriver, as discussed above. In the illustrated embodiment, a mechanismfor selective automatic shifting of the third shift rail 22 will bedisclosed in detail. However, it will be appreciated that the selectiveautomatic shifting structure of this invention could be easily adaptedto effect shifting of any of the shift rails 20, 21, and 22. It will befurther appreciated that the selective automatic shifting structure ofthis invention could also be adapted to effect shifting of more than oneor all of the shift rails 20, 21, and 22 on an individual basis.

3. Idler Rail

The selective automatic shifting structure of this invention includes anidler rail 30 which, as best shown in FIGS. 2 through 4, is disposedbetween the second shift rail 21 and the third shift rail 22. As withthe shift rails 20, 21, and 22, the ends of the idler rail 30 extendthrough respective openings formed through the front and rear railsupport members 23 and 24. Thus, the idler rail 30 is also axiallymovable from a central neutral position to either a forward position (tothe left when viewing FIG. 1) or to a rearward position (toward theright when viewing FIG. 1). Forward and rearward notches 30a and 30b areformed in the upper surface of the idler rail 30. The forward notch 30ais transversely aligned with the forward notches 20a, 21a, and 22a whenall of the rails 20, 21, 22, and 30 are in their neutral positions.Similarly, the rearward notch 30b is transversely aligned with therearward notches 20b, 21b, and 22b when all of the rails 20, 21, 22, and30 are in their neutral positions.

Unlike the conventional manual transmission described above, the lowerend of the shift lever 14 in the illustrated transmission 10 isprevented from cooperating with the forward notch 22a formed in thethird shift rail 22. Rather, the lower end of the shift lever 14 ispermitted to selectively cooperate only with the forward notches 20a,21a, and 30a respectively formed in the upper surfaces of the rails 20,21, and 30. The specific structure for accomplishing this, and thereasons therefor, will be explained below.

To manually operate the transmission 10, the driver initially selectsone of the three rails 20, 21, and 30 for movement. This is accomplishedby pivoting the lower end of the shift lever 14 in a direction which istransverse to the longitudinal axes of the rails 20, 21, and 30. Byappropriate pivoting movement in this selecting direction, the lower end14 of the shift lever is positioned in a single one of the forwardnotches 20a, 21a, and 30a formed in the rails 20, 21, and 30,respectively.

Following this initial selection movement, the driver then shifts theselected rail 20, 21, and 30 by pivoting the lower end of the shiftlever 14 in a direction which is parallel to the longitudinal axesthereof. By appropriate pivoting movement in this shifting direction,the selected one of the rails 20, 21, and 30 is then moved axiallyforwardly or rearwardly from the central neutral position. When thefirst shift rail 20 is selected and shifted in this manner, one or theother of the lowest gear ratios available therefrom are engaged, asdescribed above. Similarly, when the second shift rail 21 is selectedand shifted in this manner, one or the other of the intermediate gearratios available therefrom are engaged. However, unlike the shift rails20 and 21, the idler rail 30 is not provided with a shift fork or othermeans for engaging a gear engaging mechanism when moved. Rather, meansare provided for selectively connecting the idler rail 30 to the thirdshift rail 22 such that movement of the idler rail 30 causescorresponding movement of the third shift rail 22. As a result, one orthe other of the highest gear ratios available from movement of thethird shift rail 22 are engaged.

4. Manual/Automatic Selector Assembly

As best shown in FIGS. 2 and 3, a manual/automatic selector assembly isprovided for selectively connecting the idler rail 30 to the third shiftrail 22. The manual/automatic selector assembly includes an automaticshift shaft 31 which is rotatably supported within the shift housing 12of the transmission 10. The automatic shift shaft 31 includes a centralkeyway 31a which extends across the opening 11a formed through the upperportion of the transmission case 11. The automatic shift shaft 31further includes an upstanding tab 31b which is formed at the rearwardend thereof (the right end when viewing FIGS. 2 and 3). The purpose ofthis upstanding tab 31b will be explained in detail below.

The manual/automatic selector assembly also includes an automatic shiftmember, indicated generally at 32, which is mounted on the automaticshift shaft 31. As best shown in FIGS. 7 and 8, the automatic shiftmember 32 includes a central body 33 which is generally hollow andcylindrical in shape. A smooth inner surface 33a of the body 33 has akeyway 33b formed therein which is complementary in size and shape withthe central keyway 31a of the automatic shift shaft 31. A key 34 (seeFIGS. 1, 2, and 3) is provided in the mating keyways 31a and 33b. Thus,the automatic shift member 32 is supported on the automatic shift shaft31 for sliding axial movement relative thereto (left and right whenviewing FIGS. 2 and 3), but is restrained by the key 34 for rotationalmovement therewith.

As also shown in FIGS. 7 and 8, the outer surface of the body 33 of theautomatic shift member 32 has an enlarged boss 35 formed at one endthereof. The outer surface of the body 33 also has a circumferentialgroove 36 formed about the other end thereof. Lastly, the automaticshift member 32 is formed having a finger 37 which extends downwardlyfrom the body 33 thereof. The depending finger 37 of the automatic shiftmember 32 is aligned with the rearward notches 20b, 21b, 22b, and 30brespectively formed in the rails 20, 21, 22, and 30. The purposes of theboss 35, the groove 36, and the finger 37 will be explained in detailbelow.

The manual/automatic selector assembly further includes a manual shiftmember, indicated generally at 40, which is supported on the automaticshift member 32. As best shown in FIGS. 9 and 10, the manual shiftmember 40 includes a central body 41 which is generally hollow andcylindrical in shape. A smooth inner surface 41a of the body 41 is sizedto be slightly larger in diameter than the outer diameter of the body 33of the automatic shift member 32. Thus, the body 41 of the manual shiftmember 40 is journalled on the body 33 of the automatic shift member 32for rotational movement relative thereto, as shown in FIGS. 2, 3, and 4.When so installed, the body 41 of the manual shift member 40 abuts theenlarged boss 35 formed on the body 33 of the automatic shift member 32.To retain the manual shift member 40 on the automatic shift member 32, asnap ring 42 is provided in the groove 36 of the body 33. Thus, it canbe seen that the combined assembly of the automatic shift member 32 andthe manual shift member 40 is axially slidable as a unit along theautomatic shift shaft 31. However, the manual shift member 40 can berotated relative to the automatic shift member 32 and the automaticshift shaft 31 keyed thereto.

As also shown in FIGS. 9 and 10, the outer surface of the body 41 of themanual shift member 40 is formed having an enlarged circumferentialflange 43 at one end thereof. First and second recesses 44 and 45 areformed in the outer surface of the flange 43. As best shown in FIG. 9,the recesses 44 and 45 extend only partially across the outer surface ofthe flange 43. Thus, a non-recessed portion of the outer surface of theflange 43 is provided directly adjacent to each of the recesses 44 and45. These non-recessed portions are indicated in dotted lines at 44a and45a in FIG. 9. The manual shift member 40 is further formed having afinger 46 which depends downwardly from the body 41 thereof. Similar tothe depending finger 37 of the automatic shift member 32, the dependingfinger 46 of the manual shift member 40 is aligned with the rearwardnotches 20b, 21b, 22b, and 30b respectively formed in the rails 20, 21,22, and 30. The purposes of the flange 43, the recesses 44 and 45, thenon-recessed surfaces 44a and 45a, and the finger 46 will be explainedin greater detail below.

Referring now to FIGS. 2 and 3, it can be seen that the combinedassembly of the automatic shift member 32 and the manual shift member 40is axially slidable along the automatic shift shaft 31 between a firstposition (illustrated in FIG. 2) and a second position (illustrated inFIG. 3). In the first position illustrated in FIG. 2, the combinedassembly of the automatic shift member 32 and the manual shift member 40is positioned for manual shifting of the third shift rail 22. In thesecond position illustrated in FIG. 3, the combined assembly of theautomatic shift member 32 and the manual shift member 40 is positionedfor automatic shifting of the third shift rail 22.

In the manual shifting position illustrated in FIG. 2, the dependingfinger 37 of the automatic shift member 32 is located out of all of therearward notches 20b, 21b, 22b, and 30b formed in the rails 20, 21, 22,and 30, respectively. Thus, rotational movement of the automatic shiftmember 32 and the automatic shift shaft 31 (in a manner described below)will have no effect on any of the components of the transmission 10. Atthe same time, however, the depending finger 46 of the manual shiftmember 40 is disposed within both the rearward notch 22b formed in thethird shift rail 22 and the rearward notch 30b formed in the idler rail30. Thus, in this position, the finger 46 of the manual shift member 40functions as a key to connect the third shift rail 22 to the idler rail30 for movement therewith. Thus, axial movement of the idler rail 30resulting from manual pivoting movement of the shift lever 14, asdescribed above, will cause corresponding axial movement of the thirdshift rail 22. Consequently, one or the other of the highest gear ratiosavailable from the third shift rail 22 will be engaged in the mannerpreviously discussed.

In the automatic shifting position illustrated in FIG. 3, the dependingfinger 37 of the automatic shift member 32 is located only within thenotch 22b formed in the third shift rail 22. Thus, rotational movementof the automatic shift member 32 and the automatic shift shaft 31 (in amanner described below) will cause axial movement of the third shiftrail 22. As a result, one or the other of the highest gear ratiosavailable from the third shift rail 22 will be engaged in the mannerpreviously discussed. At the same time, however, the depending finger 46of the manual shift member 40 is disposed only within the notch 30bformed in the idler rail 30. As mentioned above, the manual shift member40 is supported on the automatic shift member 32 for relative rotationalmovement. Thus, when the third shift rail 22 is moved automatically asdescribed above, the automatic shift member 32 is rotated relative tothe manual shift member 40. Consequently, the idler rail 30 is not movedwith the third shift rail 22, but rather remains stationary. Theimportance of this disconnection of the idler rail 30 from the thirdshift rail 22 when the transmission 10 is operated in the automatic modewill be explained below.

Means are provided for selectively moving the combined assembly of theautomatic shift member 32 and the manual shift member 40 between thefirst and second positions discussed above to select operation in eitherthe manual or automatic shifting modes. As best shown in FIGS. 2 and 3,this means for selectively moving includes a pair of mode selectingpistons 50 and 51 which are slidably disposed in respective chambers 52and 53 defined in the shift housing 12. The mode selecting pistons 50and 51 have respective generally cylindrical recesses 50a and 51a formedtherein which face one another. A pin 54 is disposed between the twomode selecting pistons 50 and 51, extending within and supported by thecorresponding recesses 50a and 51a. Also, a portion of the flange 43 ofthe manual shift member 40 is captured between portions of the two modeselecting pistons 50 and 51. Thus, by moving the mode selecting pistons50 and 51 within their respective chambers 52 and 53, the combinedassembly of the automatic shift member 32 and the manual shift member 40can be moved between the first and second positions.

A simplified schematic diagram of a fluid actuated control circuit isillustrated in FIGS. 2 and 3 for causing movement of the combinedassembly of the automatic shift member 32 and the manual shift member 40between the first and second positions. The fluid control circuitincludes a first port 55 formed in the chamber 52 and a second port 56formed in the chamber 53. The first port 55 communicates through aconduit 55a to a first outlet of a conventional two-way, two-positionvalve 57. The second port 56 communicates through a conduit 56a to asecond outlet of the valve 57. A first inlet of the valve 57 isconnected to a source of pressurized air 58. A second inlet of the valve57 is vented to the atmosphere. Alternatively, the first inlet of thevalve 57 may be connected to a source of pressurized hydraulic fluid, inwhich case the second inlet of the valve 57 would be vented to areservoir.

In either event, the valve 57 is manually movable by the driver of thevehicle between a first position illustrated in FIG. 2 and a secondposition illustrated in FIG. 3. In the first position, pressurized airis supplied to the right chamber 53, while the left chamber 52 is ventedto the atmosphere. As a result, the mode selecting piston 51 urges thepin 54, the mode selecting piston 50, and the combined assembly of theautomatic shift member 32 and the manual shift member 40 toward the leftinto the first position illustrated in FIG. 2 for operation in themanual shifting mode. To change to the automatic shifting mode, thedriver moves the valve 57 to the second position illustrated in FIG. 3.When so moved, pressurized air is supplied to the left chamber 52, whilethe right chamber 53 is vented to the atmosphere. As a result, the modeselecting piston 50 urges the pin 54, the mode selecting piston 51, andthe combined assembly of the automatic shift member 32 and the manualshift member 40 toward the right into the second position illustrated inFIG. 3 for operation in the automatic shifting mode.

5. Automatic Shifting Assembly

Having described the structure of the manual/automatic selector assemblyand how such assembly is moved between the manual shifting positionillustrated in FIG. 2 and the automatic shifting position illustrated inFIG. 3, the structure for effecting the automatic shifting of the thirdshift rail 22 will now be described. To accomplish this, an automaticshifting assembly is provided for selectively rotating the automaticshift shaft 31 when the combined assembly of the automatic shift member32 and the manual shift member 40 is located in the automatic shiftingposition illustrated in FIG. 3. This automatic shifting assembly is bestillustrated in FIGS. 4, 5, and 6.

As shown therein, the automatic shifting assembly includes a firstcylindrical recess, indicated generally at 60, which is formed in theshift housing 12. The first cylindrical recess 60 is closed by afluid-tight sealing plate 61 secured to the outer surface of the shifthousing 12. Within the first cylindrical recess 60, a first automaticshift piston assembly is disposed. The first automatic shift pistonassembly includes an outer piston 62, a piston rod 63 having anelongated stem portion, and an inner piston 64. The outer piston 62 ispress fit onto the piston rod 63 for movement therewith. The elongatedstem portion of the piston rod 63 extends through the inner piston 64and is axially movable relative thereto. The outer piston 62 sealinglyengages the wall of the first cylindrical recess 60 so as to divide itinto two fluid-tight chambers 60a and 60b. The chamber 60a is definedbetween the sealing plate 61 and the outer piston 62, while the chamber60b is defined between the outer piston 62 and the inner piston 64.

Similarly, a second cylindrical recess, indicated generally at 65, isalso formed in the shift housing 12. The second cylindrical recess 65 isclosed by a fluid-tight sealing plate 66 secured to the outer surface ofthe shift housing 12. Within the second cylindrical recess 65, a secondautomatic shift piston assembly is disposed. The second automatic shiftpiston assembly includes an outer piston 67, a piston rod 68 having anelongated stem portion, and an inner piston 69. The outer piston 67 ispress fit onto the piston rod 68 for movement therewith. The elongatedstem portion of the piston rod 68 extends through the inner piston 69and is axially movable relative thereto. The outer piston 67 sealinglyengages the wall of the second cylindrical recess 65 so as to divide itinto two fluid-tight chambers 65a and 65b. The chamber 65a is definedbetween the sealing plate 66 and the outer piston 67, while the chamber65b is defined between the outer piston 67 and the inner piston 69.

Between the first and second automatic shift piston assemblies, anautomatic shift block 70 is provided. The automatic shift block 70 isslidably disposed within an intermediate chamber 71 defined within theshift housing 12 and extending between the cylindrical recesses 60 and65. The ends of the automatic shift block 70 are formed having first andsecond recesses 70a and 70b which are sized to receive the innermostends of the elongated stem portions of the piston rods 62 and 67. Theautomatic shift block 70 is further formed having a third recess 70cwhich is sized to receive the upstanding tab 31b of the automatic shiftshaft 31 therein. Thus, as best shown in FIGS. 5 and 6, axial slidingmovement of the automatic shift block 70 toward the left causescounter-clockwise rotational movement of the automatic shift shaft 31.Similarly, axial sliding movement of the automatic shift block 70 towardthe right causes clockwise rotational movement of the automatic shiftshaft 31.

A fluid actuated control circuit is illustrated in FIG. 4 forselectively effecting this axial sliding movement of the automatic shiftblock 70 and, thus, the rotational movement of the automatic shift shaft31. The fluid control circuit includes a first port 80 which is formedin the chamber 60a defined between the sealing plate 61 and the outerpiston 62. The fluid control circuit also includes a second port 81which is formed in the chamber 65a defined between the sealing plate 66and the outer piston 67. The fluid control circuit further includes athird port 82 which is located in the chamber 60b defined between theouter piston 62 and the inner piston 64. Lastly, the fluid controlcircuit includes a fourth port 83 which is located in the chamber 65bdefined between the outer piston 67 and the inner piston 69.

The first port 80 communicates through a conduit 80a to a first solenoidoperated valve 85. The second port 81 communicates through a conduit 81ato a second solenoid operated valve 86. The third port 82 and the fourthport 83 communicate through a common conduit 82a to a third solenoidoperated valve 87. Each of the solenoid operated valves 85, 86, and 87is connected to a source of pressurized fluid 88, such as pressurizedair, through a common inlet line 89. The source of pressurized air 88may be the same as the source of pressurized air 58 described above. Thesolenoid operated valves 85, 86, and 87 are conventional in the art andare provided to selectively control the flow of the pressurized airtherethrough from the source 88 to each of the ports 80, 81, 82, and 83.

To slide the automatic shift block 70 axially toward the left (resultingin counter-clockwise rotational movement of the automatic shift shaft31), the second solenoid operated valve 86 is energized to permitpressurized air from the source 88 to enter the chamber 65a through theport 81. At the same time, the first and third solenoid operated valves85 and 87 are de-energized to respectively vent the chambers 60a, 60b,and 65b from the ports 80, 82, and 83 to the atmosphere. The resultantpressure differential across the outer piston 67 causes it and thepiston rod 68 to slide to the left. After a predetermined amount of freesliding, the inner end of the piston rod 68 received in the secondrecess 70b engages the automatic shift block 70, sliding it to the leftas shown in FIG. 6. Consequently, the automatic shift shaft 31 isrotated in the counter-clockwise direction.

To slide the automatic shift block 70 axially toward the right(resulting in clockwise rotational movement of the automatic shift shaft31), the first solenoid operated valve 85 is energized to permitpressurized air from the source 88 to enter the chamber 60a through theport 80. At the same time, the second and third solenoid operated valves86 and 87 are de-energized to respectively vent the chambers 65a, 60b,and 65b from the ports 81, 82, and 83 to the atmosphere. The resultantpressure differential across the outer piston 62 causes it and thepiston rod 63 to slide to the right. After a predetermined amount offree sliding, the inner end of the piston rod 63 received in the firstrecess 70a engages the automatic shift block 70, sliding it to theright. Consequently, the automatic shift shaft 31 is rotated in theclockwise direction.

To position the automatic shift block 70 in the central neutral positionillustrated in FIGS. 4 and 5, the third solenoid operated valve 87 isenergized to permit pressurized air from the source 88 to enter thechambers 60b and 65b through the ports 82 and 83. At the same time, thefirst and second solenoid operated valves 85 and 86 are de-energized torespectively vent the chambers 60a and 65a from the ports 80 and 81 tothe atmosphere. The resultant pressure differentials cause the outer andinner pistons 62 and 64 to slide apart from one another within the firstcylindrical recess 60, and further cause the outer and inner pistons 67and 69 to slide apart from one another within the second cylindricalrecess 65. Thus, the inner pistons 64 and 69 are moved inwardly towardone another and engage the ends of the automatic shift block 70. As aresult, the automatic shift block 70 is positioned in the neutralposition illustrated in FIGS. 4 and 5, and the automatic shift shaft 31is rotated to the neutral position as well.

6. Automatic Shift Position Sensor

To facilitate the operation of the transmission 10, it is desirable thatthe automatic shifting assembly described above be operated only whenthe highest gear ratios are selected by the driver of the vehicle. Ifthe transmission 10 is a single stage, five speed transmission, thehighest gear ratios are fourth and fifth. If the transmission 10 is acompound, ten speed transmission, the highest gear ratios are ninth andtenth. In either embodiment, means are provided for generating anelectrical signal when the highest gear ratios are selected by thedriver of the vehicle.

This means for generating an electrical signal includes an automaticshift position sensor 90 which, as best shown in FIGS. 11 through 13, ismounted in the shift housing 12. The automatic shift position sensor 90is conventional in the art and is designed to generate an electricalsignal whenever the manual shift finger 40 is rotated out of the neutralposition to a gear engaging position. To accomplish this, theillustrated automatic shift position sensor 90 is provided with aninternal movable ball 91. The ball 91 is urged outwardly from theautomatic shift position sensor 90 into engagement with the outersurface of the flange 43 formed on the manual shift member 40.

When the idler rail 30 and the manual shift member 40 are in the neutralposition illustrated in FIG. 11, the recesses 44 and 45 formed in theouter surface of the flange 43 are not aligned with the automatic shiftposition sensor 90. Because it is urged into engagement with the outersurface of the flange 43, the ball 91 is located in a first retractedposition relative to the automatic shift position sensor 90. Meansprovided within the automatic shift position sensor 90 are responsive tothis retracted position of the ball 91 for generating a first electricaloutput signal.

When the idler rail 30 and the manual shift member 40 are moved out ofthe neutral position into one of the gear engaging positions, twooutcomes are possible. The first outcome, illustrated in FIG. 12, occurswhen the driver of the vehicle desires manual operation of the highestgear ratios of the transmission 10. As discussed above, the combinedassembly of the automatic shift member 32 and the manual shift member 40is located in the first position illustrated in FIG. 2 for such manualoperation. If the manual shift member 40 is located in this positionwhen the idler rail 30 is moved out of the neutral position, then thenon-recessed outer surface 44a of the flange 43 (located adjacent to therecess 44) becomes aligned with the automatic shift position sensor 90.As a result, the ball 91 is maintained in its first retracted position.Thus, the automatic shift position sensor 90 continues to generate thefirst electrical output signal.

The second outcome, illustrated in FIG. 13, occurs when the driver ofthe vehicle desires automatic operation of the highest gear ratios ofthe transmission 10. As discussed above, the combined assembly of theautomatic shift member 32 and the manual shift member 40 is located inthe second position illustrated in FIG. 3 for such automatic operation.If the manual shift member 40 is located in this position when the idlerrail 30 is moved out of the neutral position, then the recess 44 formedin the outer surface of the flange 43 becomes aligned with the automaticshift position sensor 90. As a result, the ball 91 is urged outwardlyinto the recess 44 and is located in a second extended position relativeto the automatic shift position sensor 90. Means provided within theautomatic shift position sensor 90 are responsive to this extendedposition of the ball 91 for generating a second electrical outputsignal.

Thus, it can be seen that the second electrical output signal will begenerated by the automatic shift position sensor 90 only when both (1)the idler rail 30 and the manual shift member 40 are moved out of theneutral position to a gear engaging position and (2) the combinedassembly of the automatic shift member 32 and the manual shift member 40is located in the second position illustrated in FIG. 3 for automaticoperation. If either of these conditions is not satisfied, the ball 91contained in the automatic shift position sensor 90 will not be receivedwithin the recess 44, and the automatic shift position sensor 90 willgenerate the first electrical output signal. The manner in which thesefirst and second electrical output signals are used to control theoperation of the automatic shifting assembly will be explained below.

7. Shifting Operation--Single Stage Transmission

The operation of the transmission 10 thus far described will now beexplained in the context of the single stage, five speed transmissiondiscussed above. To operate the transmission 10 manually, the driver ofthe vehicle initially moves the valve 57 to the first positionillustrated in FIG. 2. As discussed above, pressurized air supplied tothe chamber 53 causes the combined assembly of the automatic shiftmember 32 and the manual shift member 40 to slide along the automaticshift shaft 31 toward the left to the manual shifting positionillustrated in FIG. 2. As a result, the depending finger 37 of theautomatic shift member 32 is located out of the notch 22b formed in thethird shift rail 22. At the same time, the depending finger 46 of themanual shift member 40 is disposed within both the notch 22b formed inthe third shift rail 22 and the notch 30b formed in the idler rail 30.Accordingly, the third shift rail 22 is connected to the idler rail 30for movement therewith, as described above.

To manually shift among the reverse and first gear ratios, the driverinitially moves the lower end of the shift lever 14 transversely toselect the first shift rail 20. Then, the driver moves the lower end ofthe shift lever 14 longitudinally to move the first shift rail 20 intoone of its two gear engaging positions. Similarly, to manually shiftamong the second and third gear ratios, the driver initially moves thelower end of the shift lever 14 transversely to select the second shiftrail 21. Then, the driver moves the lower end of the shift lever 14longitudinally to move the second shift rail 21 into one of its two gearengaging positions.

To manually shift among the fourth and fifth gear ratios, the driverinitially moves the lower end of the shift lever 14 transversely toselect the idler rail 30, not the third shift rail 22. Subsequently, thedriver moves the lower end of the shift lever 14 longitudinally to movethe idler rail 30 into one of its two gear engaging positions. Becauseof the key-like engagement of the depending finger 46 of the manualshift member 40 with both the idler rail 30 and the third shift rail 22,such longitudinal movement of the idler rail 30 causes correspondinglongitudinal movement of the third shift rail 22 into one of its twogear engaging positions. As previously discussed, the depending finger37 of the automatic shift member 32 is located out of the notch 22bformed in the third shift rail 22 and, thus, has no effect on theoperation of the transmission 10 during manual shifting. Throughout thisentire process, the automatic shift position sensor 90 generates thefirst electrical output signal, as described above.

To operate the transmission 10 automatically, the driver of the vehicleinitially moves the valve 57 to the second position illustrated in FIG.3. As discussed above, pressurized air supplied to the chamber 52 causesthe combined assembly of the automatic shift member 32 and the manualshift member 40 to slide along the automatic shift shaft 31 toward theright to the automatic shifting position illustrated in FIG. 2. As aresult, the depending finger 37 of the automatic shift member 32 islocated within the notch 22b formed in the third shift rail 22, whilethe depending finger 47 of the manual shift member 40 is located withinthe notch 30b formed in the idler rail 30.

To manually shift among the reverse and first gear ratios and among thesecond and third gear ratios, the driver follows the procedure discussedabove. However, to automatically shift among the fourth and fifth gearratios, the driver need only move the lower end of the shift lever 14transversely to select the idler rail 30, then pivot the shift lever 14to move the manual shift member 40 to the gear engaging positionillustrated in FIG. 13. When this occurs, the automatic shift positionsensor 90 generates the second electrical signal, as discussed above. Inresponse thereto, the automatic shifting assembly described above isoperated to selectively cause clockwise and counter-clockwise rotationalmovement of the automatic shift shaft 31. As discussed above, thedepending finger 37 of the automatic shift member 32 (which is keyed tothe automatic shift shaft 31 for rotational movement therewith) islocated within the notch 22b formed in the third shift rail 22.Consequently, clockwise and counter-clockwise rotation of the automaticshift shaft 31 causes corresponding forward and rearward longitudinalmovement of the third shift rail 22 into its two gear engagingpositions.

While this automatic shifting of the highest two gear ratios isoccurring, it will be recalled that the depending finger 46 of themanual shift member 40 is disposed only within the notch 30b formed inthe idler rail 30. Thus, the idler rail 30 is effectively disconnectedfrom the third shift rail 22. As a result, when the third shift rail 22is shifted automatically as described above, the idler rail 30 and themanual shift member 40 remain stationary. This is desirable because ifthe idler rail 30 remained connected to the third shift rail 22, thenthe upper portion of the shift lever 14 would pivot back and forth asthe third shift rail 22 is automatically shifted. Such movement of theshift lever 14 would constitute an undesirable distraction and annoyanceto the driver of the vehicle. Thus, the structure of this inventionallows the shift lever 14 to remain stationary even though the thirdshift rail 22 is automatically shifted.

8. Shifting Operation--Compound Transmission

The operation of the transmission 10 thus far described will now beexplained in the context of the compound, ten speed transmissiondiscussed above. FIG. 14 illustrates a schematic diagram of a fluidcontrol system for use with such a compound transmission. As showntherein, the shift lever 14 is provided with a handle 14a upon which arange select switch 95 is mounted. The range select switch isconventional in the art and is connected to a pilot control valve (notshown) contained within the handle of the shift lever 14. The pilotcontrol valve may be embodied as the two-way, two-position valve 57described above. Thus, manual operation of the range select switch 95causes movement of the valve 57 as described above.

In the illustrated embodiment, the conduits 55a and 55b are connectednot only to the valve 57 as described above, but also are connected to arange shift control valve 96. The range shift control valve 96 isconventional in the art and is provided to control the operation of aconventional range shifter 97. When the valve 57 is moved to the firstposition illustrated in FIG. 2, pressurized air is supplied through theconduit 56a not only to the chamber 53 as described above, but also toone side of the range shift control valve 96. In response thereto, therange shift control valve 96 is moved to a first position, which causesthe range shifter 97 to place the auxiliary section of the transmission10 in the low gear ratio range. When the valve 57 is moved to the secondposition illustrated in FIG. 3, pressurized air is supplied through theconduit 55a not only to the chamber 52 as described above, but also tothe other side of the range shift control valve 96. In response thereto,the range shift control valve 96 is moved to a second position, whichcauses the range shifter 97 to place the auxiliary section of thetransmission 10 in the high gear ratio range.

To operate the compound transmission 10, the driver of the vehicleinitially moves the valve 57 to the first position illustrated in FIG.2. As discussed above, pressurized air supplied to the chamber 53 causesthe combined assembly of the automatic shift member 32 and the manualshift member 40 to slide along the automatic shift shaft 31 toward theleft to the manual shifting position illustrated in FIG. 2. As a result,the depending finger 37 of the automatic shift member 32 is located outof the notch 22b formed in the third shift rail 22. At the same time,the depending finger 46 of the manual shift member 40 is disposed withinboth the notch 22b formed in the third shift rail 22 and the notch 30bformed in the idler rail 30. Accordingly, the third shift rail 22 isconnected to the idler rail 30 for movement therewith, as describedabove. Also, the auxiliary section of the transmission 10 is placed inthe low gear ratio range, as described above.

To manually shift among the reverse and first gear ratios, the secondand third gear ratios, and the fourth and fifth gear ratios, the driverfollows the procedure discussed above with respect to the single-stagetransmission. It will be appreciated that even when the fourth and fifthgear ratios are selected, the automatic shift position sensor 90continues to generate the first electrical output signal, as discussedabove. While still in the fifth gear ratio, but in anticipation ofshifting into the sixth gear ratio, the driver moves the valve 57 fromthe first position to the second position. This has the effect ofpreparing the range shifter to change from the low gear ratio range tothe high gear ratio range as soon as the idler rail 30 is returned tothe neutral position. This also has the effect of preparing themanual/automatic shifting assembly to move the combined assembly of theautomatic shift member 32 and the manual shift member 40 from the firstposition illustrated in FIG. 2 to the second position illustrated inFIG. 3 as soon as the idler rail 30 is returned to the neutral position.

To manually shift to the sixth gear ratio, the driver initially movesthe lower end of the shift lever 14 transversely to select the firstshift rail 20. Then, the driver moves the lower end of the shift lever14 longitudinally to move the first shift rail 20 into its gear engagingposition. Similarly, to manually shift among the seventh and eighth gearratios, the driver initially moves the lower end of the shift lever 14transversely to select the second shift rail 21. Then, the driver movesthe lower end of the shift lever 14 longitudinally to move the secondshift rail 21 into one of its two gear engaging positions.

To shift among the ninth and tenth gear ratios, the driver initiallymoves the lower end of the shift lever 14 transversely to select theidler rail 30, then pivots the shift lever 14 to move the manual shiftmember 40 to the gear engaging position illustrated in FIG. 13. Whenthis occurs, the automatic shift position sensor 90 generates the secondelectrical output signal, as described above. Subsequently, theautomatic shift shaft 31 (and the automatic shift member 32 keyedthereto) is automatically rotated by the automatic shifting assembly tomove the third shift rail 22 into one of its two gear engagingpositions. Thus, shifting among the ninth and tenth gear ratios isperformed automatically when the manual shift member 40 is moved to thegear engaging position, as described above.

Because the valve 57 controls both the operation of the manual/automaticshifting assembly and the range shifter 97, the above describedstructure always provides for automatic shifting between the ninth andtenth gear ratios when the manual shift member 40 is moved to the gearengaging position by the driver, as described above. In some instances,however, it may be desirable to override such automatic shifting topermit manual shifting between the ninth and tenth gear ratios. This canbe achieved by providing separate valves for individually controllingthe operations of the manual/automatic shifting assembly and the rangeshifter 97. Alternatively, an override valve (not shown) can be placedin the conduits 55a and 56a between the valve 57 and themanual/automatic shifting assembly to prevent the combined assembly ofthe automatic shift member 32 and the manual shift member 40 from movingout of the first position illustrated in FIG. 2 when the valve 57 ismoved to the second position. Lastly, a disable switch (not shown) maybe connected to the output of the automatic shift position sensor 90 toprevent the second electrical output signal from being transmittedtherefrom.

9. Shift Lever Restraining Plate

As discussed above, the lower end of the shift lever 14 cooperates withthe forward notches 20a, 21a, 22a, and 30a of the respective rails 20,21, 22, and 30. As also discussed above, such forward notches 20a, 21a,22a, and 30a are aligned with one another in a direction which istransverse to the longitudinal axes of the rails 20, 21, 22, and 30 whensuch rails 20, 21, 22, and 30 are all in their neutral positions.Because of such alignment, there is no positive stop provided on therails 20, 21, 22, and 30 for limiting the transverse movement of thelower end of the shift lever 14 during the selecting process.

To address this, a shift lever restraining plate 100 is provided on thetransmission 10. As best shown in FIG. 1, the shift lever restrainingplate 100 is disposed on the upper portion of the transmission case 11about the opening 11a. Any conventional means, such as bolts (notshown), may be used to secure the shift lever restraining plate 100 tothe case 11.

The structure of the shift lever restraining plate 100 is bestillustrated in FIG. 15. As shown therein, the shift lever restrainingplate 100 has a front opening 101a and a rear opening 101b formedtherethrough, both of which are generally rectangular in shape. Thefront opening 101a is provided to accommodate the lower end of the shiftlever 14, which extends therethrough into cooperation with the forwardnotches 20a, 21, 22a, and 30a. The rear opening 101b is provided toaccommodate the depending fingers 37 and 46 of the automatic shiftmember 32 and the manual shift member 40, respectively, which extendtherethrough into cooperation with the rearward notches 20b, 2b, 22b,and 30b. A first pair of slots 102 are formed in the front edge of theopening 101, and a second pair of slots 103 are formed in the rear edgeof the opening 101. Also, an inwardly extending boss 104 is formed onone side edge of the opening 101.

An interlock bracket 105 is mounted on the shift lever restraining plate100 for sliding movement relative thereto. The interlock bracket 105includes a first pair of tabs 106 which extend over the front edge ofthe opening 101 and a second pair of tabs 107 which extend over the rearedge of the opening 101. The tabs 106 and 107 support the interlockbracket 105 on the shift lever restraining plate 100 for slidingmovement to the left and right when viewing FIG. 15. The slots 102 and103 receive the tabs 106 and 107 when the interlock bracket 105 isinitially installed on the shift lever restraining plate 100 from below.

As best shown in FIGS. 16 and 17, the interlock bracket 105 furtherincludes a pair of downwardly extending legs 108 and 109. The legs 108and 109 are adapted to receive the lower end of the shift lever 14therebetween as it extends downwardly through the front opening 101a. Asa result, the interlock bracket 105 slides left and right with the lowerend of the shift lever 14 when the shift lever 14 is moved by the driverin a direction which is transverse to the longitudinal axes of the rails20, 21, 22, and 30. When the lower end of the shift lever 14 is movedinto the forward notch 30a of the idler rail 30, as shown in FIG. 16,the legs 108 and 109 of the interlock bracket 105 extend into thenotches 20a and 21a of the first and second shift rails 20 and 21. Thus,the first and second shift rails 20 and 21 are prevented from moving outof their neutral positions. Similarly, when the lower end of the shiftlever 14 is moved into the forward notch 21a of the second shift rail21, as shown in FIG. 17, the legs 108 and 109 of the interlock bracket105 extend into the notches 30a and 20a of the idler rail 30 and thefirst shift rail 20. Thus, the idler rail 30 and the first shift rail 20are prevented from moving out of their neutral positions. The idler rail30 and the second shift rail 21 are prevented from moving out of theirneutral positions when the lower end of the shift lever 14 is moved intothe forward notch 20a of the first shift rail 20.

As shown in FIGS. 15 and 16, the interlock bracket 105 engages the boss104 formed on the side edge of the shift lever restraining plate 100when the lower end of the shift lever 14 is moved into the forward notch30a of the idler rail 30. This engagement provides a positive stop forthe shift lever 14, preventing further movement thereof toward the left.Thus, the shift lever restraining plate 100 and the interlock bracket105 function to limit the transverse movement of the lower end of theshift lever 14 during the selecting process.

10. Automatic Shift Rail Position Sensing

To best control the automatic shifting process, it is desirable togenerate an electrical signal which is representative of the actualposition of the third shift rail 22. To accomplish this, means areprovided in the transmission 10 for sensing the rotational position ofthe automatic shift shaft 31. As shown in FIGS. 2, 3, and 18, this meansfor sensing includes a sensor bracket 110 which is secured to the end ofthe automatic shift shaft 31 by a threaded fastener 111. Thus,rotational movement of the automatic shift shaft 31 causes pivotingmovement of the sensor bracket 110. The sensor bracket 110 is generallyL-shaped in cross section, having a plurality of permanent magnets 112,113, 114, and 115 mounted thereon. The magnets 112, 113, 114, and 115are positioned on the sensor bracket 110 such that when the automaticshift shaft 31 is rotated, the magnets 112, 113, 114, and 115 are movedin an arc-like manner past a pair of sensors 116 and 117 mounted on thecase 11 of the transmission 10.

Preferably, the magnets 112, 113, 114, and 115 are arranged such thatoutermost magnets 112 and 115 present one pole (the south pole, forexample) toward the sensors 116 and 117, while the innermost magnets 113and 114 present the opposite pole (the north pole, for example) towardthe sensors 116 and 117. When the magnets 112, 113, 114, and 115 aremoved past the sensor 116, the sensors 116 and 117 generate electricalsignals. For example, assume that the sensors 116 and 117 generate alogical low or "0" output signal when the south pole magnets 112 or 115are moved adjacent thereto and generate a logical high or "1" outputsignal when the north pole magnets 113 or 114 are moved adjacentthereto.

When the automatic shift shaft 31 is in the neutral position illustratedin FIG. 18, the north pole magnets 113 and 114 are respectively locatedadjacent to the sensors 116 and 117. Thus, both sensors 116 and 117generate a logical high or "1" output signal. This logical "1--1" outputsignal can be used to indicate that the automatic shift shaft 31 is inthe neutral position. When the automatic shift shaft 31 is rotatedclockwise as previously discussed, the south pole magnet 112 is movedadjacent to the sensor 116, while the north pole magnet 113 is movedpast the sensor 117. Thus, the sensor 116 generates a logical low or "0"output signal, while the sensor 117 generates a logical high or "1"output signal. This logical "0-1" output signal can be used to indicatethat the automatic shift shaft 31 is in a first gear engaging position.Similarly, when the automatic shift shaft 31 is rotatedcounter-clockwise as previously discussed, the north pole magnet 114 ismoved past the sensor 116, while the south pole magnet 115 is movedadjacent to the sensor 117. Thus, the sensor 116 generates a logicalhigh or "1" output signal, while the sensor 117 generates a logical lowor "0" output signal. This logical "1-0" output signal can be used toindicate that the automatic shift shaft 31 is in a second gear engagingposition.

Although any conventional sensors which are responsive to movement ofthe magnets 112, 113, 114, and 115 may be used, the sensors 116 and 117are preferably embodied as Hall effect latch sensors. Such Hall effectlatch sensors 116 and 117 not only generate predetermined output signalsdepending upon the particular pole of the magnet presented to it, butfurther latch into that condition and hold it until an opposite polemagnet is moved adjacent thereto. Thus, when the automatic shift shaft31 is rotated from the neutral position to one of the gear engagingpositions, the sensors 116 and 117 will continue to generate the logical"1--1" output signal until one of the south pole magnets 112 or 115 ismoved adjacent thereto. Thus, it is insured that the shifting process isfully completed before the sensors generate the logical "1-0" or "0-1"output signal. For example, the Hall effect latch sensors may beembodied as Type UGN-3035U sensors from Sprague Electric Company.

11. Electronic Control

Referring now to FIG. 19, there is illustrated a simplified schematicdiagram of an electronic control circuit, indicated generally at 120,for use with the above-described transmission 10. The electronic controlcircuit 120 includes a microprocessor 121 or similar electroniccontroller which can be programmed to generate one or more electricaloutput signals in response to a plurality of electrical input signals. Afirst input signal to the microprocessor 121 is provided from theautomatic shift position sensor 90, which is representative of whethermanual or automatic shifting is to be performed. Second and third inputsignals are provided from the sensors 116 and 117, which arerepresentative of the rotational position of the automatic shift shaft31 and, therefore, the axial position of the idler rail 30. Lastly,additional input signals may be provided from one or more vehicleoperating parameter sensors 122 located within the vehicle. Such vehicleoperating parameters may include engine speed, road speed, throttleposition, brake actuation, and the like.

The microprocessor 121 performs a pre-programmed routine to analyze thevarious input signals supplied thereto to generate appropriate outputsignals to the solenoid operated valves 85, 86, and 87. In responsethereto, the solenoid operated valves 85, 86, and 87 are operated asdescribed above to automatically shift the third shift rail 22. Anypre-programmed routine may be employed to accomplish this, and a personhaving ordinary skill in the art would be able to construct an operableroutine. The pre-programmed routine itself forms no part of thisinvention.

12. Forward/Center Operation

Throughout the preceding discussion, the transmission 10 has beenexplained and illustrated with the shift lever 14 extending intocooperation with the forward notches 20a, 21a, 22a, and 30a of theassociated rails 20, 21, 22, and 30. When configured in this manner, theshift lever 14 extends upwardly from the forward portion of thetransmission 10. However, as is well known in the art, it is sometimesdesirable to have the shift lever extend upwardly from the centralportion of the transmission 10. In the past, this has been accomplishedby reversing the orientation of the shift housing 12 one hundred eightydegress relative to the case 11. Thus, in this structure, the shiftlever 14 would extend into cooperation with the rearward notches 20b,21b, 22b, and 30b of the associated rails 20, 21, 22, and 30. At thesame time, the automatic shift member 32 and the manual shift member 40would extend into cooperation with the forward notches 20a, 21a, 22a,and 30a of the associated rails 20, 21, 22, and 30.

As discussed above, the outer surface of the flange 43 is also formedhaving a second recess 45 and associated non-recessed surface 45a. Whenthe transmission 10 is configured for operation as described andillustrated above, the recess 45 and non-recessed surface 45a areunused. However, when the transmission 10 is re-configured by reversingthe orientation of the shift housing 12, the recess 45 and non-recessedsurface 45a are employed by the automatic shift position sensor 90 toselectively generate the first and second electrical output signals,instead of the recess 44 and non-recessed surface 44a.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

What is claimed is:
 1. A transmission comprising:an input shaft; anoutput shaft; a gear engaging mechanism selectively operable in a firstcondition, wherein said input shaft is not connected to said outputshaft, and a second condition, wherein said input shaft is connectedthrough said gear engaging mechanism to said output shaft; a shift railmovable between a first shift rail position, wherein said gear engagingmechanism is operated in said first condition, and a second shift railposition, wherein said gear engaging mechanism is operated in saidsecond condition; a shift shaft having a shift member mounted thereonfor rotation with said shift shaft and for axial movement relativethereto between a first shift member position, wherein said shift memberis engaged with said shift rail, and a second shift member position,wherein said shift member is disengaged from said shift rail; means forselectively rotating said shift shaft when said shift shaft is locatedin said first shift member position so as to cause movement of saidshift rail between said first and second shift rail positions; and meansresponsive to rotation of said shift member for generating a signalwhich is representative of the relative position of said shift rail. 2.The transmission defined in claim 1 wherein said means for selectivelyrotating includes means for connecting said shift member to said shiftshaft for movement therewith.
 3. The transmission defined in claim 2wherein said means responsive to movement of said shift shaft includes amagnet connected for movement with said shift shaft and a sensorresponsive to movement of said magnet for generating said electricalsignal.
 4. The transmission defined in claim 2 wherein said meansresponsive to movement of said shift shaft includes a plurality ofmagnets connected for movement with said shift shaft and a sensorresponsive to movement of said magnets for generating said electricalsignal.
 5. The transmission defined in claim 4 wherein said magnets havediffering polarities.
 6. The transmission defined in claim 2 whereinsaid means responsive to movement of said shift shaft includes aplurality of magnets connected for movement with said shift shaft and aplurality of sensors responsive to movement of said magnets forgenerating said electrical signal.
 7. The transmission defined in claim6 wherein said magnets have differing polarities.
 8. The transmissiondefined in claim 1 further including means for moving said shift memberbetween said first and second shift member positions.
 9. Thetransmission defined in claim 8 wherein said means for moving includes afirst chamber, a first piston slidably disposed within said firstchamber, and means for urging said first piston into engagement withsaid shift member so as to move said shift member from said first shiftmember position to said second shift member position.
 10. Thetransmission defined in claim 9 wherein said means for urging said firstpiston includes a source of pressurized fluid and means for selectivelyproviding communication between said source of pressurized fluid andsaid first chamber.
 11. The transmission defined in claim 9 wherein saidmeans for moving further includes a second chamber, a second pistondisposed within said second chamber for sliding movement, and means forurging said second piston into engagement with said shift member so asto move said shift member from said second shift member position to saidfirst shift member position.
 12. The transmission defined in claim 11wherein said means for urging said second piston includes a source ofpressurized fluid and means for selectively providing communicationbetween said source of pressurized fluid and said second chamber. 13.The transmission defined in claim 8, wherein said means for movingincludes a first chamber, a first piston slidably disposed within saidfirst chamber, a second chamber, a second piston slidably disposedwithin said second chamber, means for selectively urging said firstpiston into engagement with said shift member so as to move said shiftmember from said first shift member position to said second shift memberposition, and means for selectively urging said second piston intoengagement with said shift member so as to move said shift member fromsaid second shift member position to said first shift member position.14. The transmission defined in claim 13 wherein said means forselectively urging includes a source of pressurized fluid and means forselectively providing communication between said source of pressurizedfluid and said first and second chambers.
 15. The transmission definedin claim 2 wherein said means responsive to movement of said shiftmember for generating a signal which is representative of the relativeposition of said shift rail is responsive to movement of said shiftshaft for generating said signal.
 16. The transmission defined in claim1 wherein said shift member is rotatably movable between said firstshift member position and said second shift member position.
 17. Thetransmission defined in claim 16 wherein said means for selectivelymoving said shift member is effective for selectively rotating saidshift member when located in said first shift member position so as tocause movement of said shift rail between said first and second shiftrail positions.
 18. The transmission defined in claim 17 wherein saidmeans responsive to movement of said shift member is responsive torotational movement of said shift member for generating said signalwhich is representative of the relative position of said shift rail. 19.The transmission defined in claim 1 wherein said means responsive tomovement of said shift member generates an electrical signal which isrepresentative of the relative position of said shift rail.
 20. Atransmission comprising:an input shaft; an output shaft; a gear engagingmechanism selectively operable in a first condition, wherein said inputshaft is not connected to said output shaft, and a second condition,wherein said input shaft is connected through said gear engagingmechanism to said output shaft; a shift rail movable between a firstshift rail position, wherein said gear engaging mechanism is operated insaid first condition, and a second shift rail position, wherein saidgear engaging mechanism is operated in said second condition; an idlerrail movable between a first idler rail position and a second idler railposition; a rotatable shift shaft; an automatic shift member mounted onsaid shift shaft for rotation therewith and for axial movement relativethereto between first and second shift member positions, said automaticshift member being not engaged with said shift rail when located in saidfirst shift member position and being engaged with said shift rail whenlocated in said second shift member position; a manual shift membermounted on said automatic shift member for axial movement therewith andfor rotational movement relative thereto between said first and secondshift member positions, said manual shift member being engaged with bothsaid idler rail and said shift rail when located in said first shiftmember position and being engaged only with said shift rail when locatedin said second shift member position; means for rotating said shiftshaft when said automatic shift member and said manual shift member arelocated in said first shift member position so as to cause movement ofsaid shift rail between said first and second shift rail positions; andmeans for moving said idler rail between said first and second idlerrail positions when said automatic shift member and said manual shiftmember are located in said second shift member position so as to causemovement of said shift rail between said first and second shift railpositions.